From 3030c1258ba1c39ced94b88958c12486be5f6c41 Mon Sep 17 00:00:00 2001
From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
Date: Wed, 20 Nov 2024 12:52:27 +0100
Subject: [PATCH 2/4] mptcpize: define error() if not available

Some libc like musl don't support it.

It is easy enough to define a simple version for our need.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 configure.ac   |  5 +++++
 src/mptcpize.c | 19 ++++++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index e1bc1ff..fd0e321 100644
--- a/configure.ac
+++ b/configure.ac
@@ -273,6 +273,11 @@ AC_CHECK_FUNC([l_netlink_message_new_sized],
                          [ELL has l_netlink_message_new_sized()])])
 LIBS=$mptcpd_save_libs
 
+# ---------------------------------------------------------------
+# Checks for header files.
+# ---------------------------------------------------------------
+AC_CHECK_HEADERS([error.h])
+
 # ---------------------------------------------------------------
 # Enable additional C compiler warnings.  We do this after all
 # Autoconf tests have been run since not all autoconf macros are
diff --git a/src/mptcpize.c b/src/mptcpize.c
index b502d75..e944729 100644
--- a/src/mptcpize.c
+++ b/src/mptcpize.c
@@ -18,7 +18,6 @@
 #include <argp.h>
 #include <dlfcn.h>
 #include <errno.h>
-#include <error.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -29,6 +28,10 @@
 # include <mptcpd/private/config.h>
 #endif
 
+#ifdef HAVE_ERROR_H
+# include <error.h>
+#endif
+
 #define SYSTEMD_ENV_VAR		"Environment="
 #define SYSTEMD_UNIT_VAR	"FragmentPath="
 #define SYSTEMD_SERVICE_TAG	"[Service]"
@@ -53,6 +56,20 @@ static char doc[] =
         "\tdisable <unit>            Update the systemd <unit>, removing\n"
         "\t                          the above launcher.\n";
 
+#ifndef HAVE_ERROR_H
+# define ERROR_HELPER(status, errnum, format, ...) do {		\
+	if (errnum) {						\
+		errno = errnum;					\
+		perror(format);					\
+	} else {						\
+		fprintf(stderr, format "%s", __VA_ARGS__);	\
+	}							\
+	if (status)						\
+		exit(status);					\
+   } while(0)
+# define error(...) ERROR_HELPER(__VA_ARGS__, "\n")
+#endif
+
 static struct argp const argp = { 0, 0, args_doc, doc, 0, 0, 0 };
 
 static void help(void)
-- 
2.45.2